#include <iostream>
#include <vector>
#include <bitset>
#include <algorithm>
using namespace std;

int dfs(int n, int col, int status)
{
        if(col == n){
                cout << bitset<4>(status)<<endl;
                return 1;
        }

     
        int ans = dfs(n, col + 1, status | (1 << col));
        ans += dfs(n, col + 1, status & ~( 1 << col));

        return ans;
}

int main()
{
        int n = 4;
        vector<int> path;
        int status = 0;
        cout << dfs(n, 0, 0) << endl;
        return 0;
}